Methods for Testing the Polishability of Materials

ABSTRACT

A method and apparatus for measuring the polishability of a solid material such as a dental restorative material includes using a series of apparatus to perform the steps of forming the material into a desired specimen with a generally planar surface, conditioning the surface by abrasion, measuring the abraded surface with a profile determination device, optionally measuring the amount of material abraded from the surface and the gloss of the abraded surface, polishing a portion of the abraded surface with a polishing device at a controlled load for a pre-determined time and measuring the roughness and/or gloss of the polished surface followed by comparison thereof to the corresponding measurements of the unpolished, conditioned portion of the specimen surface. Polishing materials and devices may also be tested using the apparatus and method for polishing a standardized material.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional application based on Ser. No. 12/571,077 filed Sep.30, 2009 entitled “Apparatus and Methods for Testing the Polishabilityof Materials” which is a utility application from previously filedprovisional application, entitled “Polishing Device Testing Apparatus”,Ser. No. 61/101,320 filed Sep. 30, 2008 all of which are incorporatedherein by reference and for which priority is claimed.

BACKGROUND OF THE INVENTION

In a principal aspect, the present invention relates to the design anduse of a system and methods directed to evaluation of the polishabilityof materials and/or the performance of polishing devices and/orinstruments in a standard, repeatable manner.

There are various clinical and laboratory evaluations reporting on thepolishability of materials (such as dental repair materials) and theperformance of polishing devices and/or instruments (such as dentaldevices); however, the evaluations rely heavily on human intervention tocontrol several important test parameters, such as applied force,contact distance and duration, and movement of the polishing equipmentin contact with the material being polished by the clinician.Furthermore, the laboratory evaluations typically lack proper feedbackcontrol mechanisms to maintain these test variables in a dynamic testingenvironment. Thus, there is a need for apparatus that properly controlsuch variables. The described system and method provide a precise andrepeatable means for evaluating the polishability of materials and/orthe performance of polishing devices and/or instruments.

SUMMARY OF THE INVENTION

The system and methods utilize the following elements: a) initialsurface finish preparation apparatus; b) surface roughness measurementapparatus; c) height measurement apparatus; d) gloss measurementapparatus; e) polishing device testing apparatus; and f) communication,control, and data processing software.

A. Initial Surface Finish Preparation Apparatus

This apparatus allows a user to prepare an initial, uniform surfacefinish to the material to be tested. The apparatus is comprised of arotating turntable with abrasive paper mounted to it. Various mountinghardware is used to position the face of the sample material parallelwith the face of the rotating turntable. The apparatus includes amotorized chucking device to allow the sample to be rotatedindependently of the rotating turntable, and a linear, motorizedtranslation stage to move the rotating sample into contact with therotating turntable. The apparatus is also comprised of a softwareprogram to control the movement and timing of the translation stage.This apparatus is depicted in FIGS. 1-6 of the drawing.

B. Surface Roughness Measurement Apparatus

This apparatus allows a user to measure and record roughness values onmultiple portions of a test specimen during the testing procedure. Theapparatus includes a mounting device that allows the test specimen to bepositioned beneath a surface profilometer with accuracy andrepeatability. The precision mounting device also allows a test specimento be mounted such that the plane corresponding to the face of the testspecimen is parallel with the measurement path of the chisel of theprofilometer. The base of the profilometer is typically mounted on amotorized, three-axis positioning stage, and the apparatus includes alifting arm attached to a linear stage that may be able to be raised andlowered in response to a computer-controlled, linear actuator. Thelifting arm allows the measuring chisel of the profilometer to come intocontact with the face of the test specimen and then be raised at theconclusion of a measurement. The apparatus also is typically operated inaccord with a software program to control the movement of the motorizedstages, the movement of the lifting arm, and collection of theprofilometer readings. FIGS. 7-11 of the drawing depict an embodiment ofthe apparatus.

C. Height Measurement Apparatus

This apparatus enables a user to measure changes in the amount ofmaterial removed from the surface of a test specimen during the testingprocedure. The apparatus includes a mounting device that allows thespecimen to be positioned in the center of a motorized rotation stagewith accuracy and repeatability. The apparatus is comprised of anelectronic height indicator mounted on a two-axis positioning table(this positioning table may be computer controlled). The electronicheight indicator is mounted on the two-axis positioning table such thatits measurement axis is perpendicular to the plane of the two-axistable. The indicating rod of the electronic height indicator may beraised and lowered from and to the surface of the test specimen,respectively, by a computer-controlled, linear actuator. The apparatustypically operates in accord with a software program to control themovement of the stage, the movement of the electronic height indicator,and collect the height measurement readings. FIGS. 12-14 of the drawingdepict an embodiment of the apparatus.

D. Gloss Measurement Apparatus

This apparatus enables a user to measure changes in gloss on the surfaceof the test specimen during the testing procedure. The apparatusincludes a mounting device that allows the specimen to be positionedover the aperture of a glossmeter with accuracy and repeatability. Themounting device is typically secured to a vertical slide (can becomputer-controlled) that allows the face of the specimen to be loweredonto the face of the glossmeter over its aperture. The vertical slide ismounted to a horizontal slide (can be computer-controlled) such that theface of the specimen can be moved parallel to the face of theglossmeter. FIG. 15 of the drawing depicts an embodiment of theapparatus.

E. Polishing Device Testing Apparatus

This apparatus enables application of a constant, programmed load by apolishing instrument or tool to a test specimen while the tool is movedin a programmed manner. The apparatus includes a mounting device thatallows the test specimen to be mounted to it with accuracy andrepeatability. This mounting device allows the specimen to be removedfrom the apparatus and then precisely remounted when required withoutlosing the original position setting. The test specimen is mounted upona force sensing holder or mount that accurately reports force applied tothe specimen. The precision mount is attached to a vertical slide thatis controlled by a motor which can move the specimen into the pathway ofa polishing instrument. Power to the motor is controlled by amicroprocessor and associated electronic hardware and software. Theapparatus allows a predetermined load to be set programmatically at anytime and maintained in accord with software in the processor. A clampholds a polishing device and/or tool and/or instrument over the surfaceof the test specimen. The clamp is affixed to a manual rotation table.The rotation table may be motorized to enable the position of the deviceand/or instrument to be computer-controlled. Once the specimen contactsthe polishing device and/or instrument, the motorized positioning tablehas the ability to move the specimen beneath the polishing device and/orinstrument for a pre-programmed time, distance, pattern and speed whilethe computer-controlled motor maintains the load on the specimen at theprogrammed setting. FIGS. 16-19 of the drawing depict an embodiment ofthis apparatus.

F. Communication, Control and Data Processing Software

The five described machines or devices may be mounted together as a teststation or mounted separately. In combination, they comprise a systemwhich accurately and with repeatability provides test data enabling theestablishment of methods for evaluating performance of materials such asdental restoratives and for comparison testing the efficacy and utilityof polishing materials and devices.

In practice, specimens in the form of a disk or cylinder with agenerally planar face transverse to the axis of the disk or cylinder areused in the conduct of the protocols associated with the devicesdescribed (see FIGS. 20A and 20B). The disk is then processed toestablish quantitative measurements of polishability in accord with thegeneral flow diagram of FIG. 21 using the described apparatus. Theresultant data is highly repeatable and thus highly desired to, forexample, establish or verify standards in a relevant field.Additionally, the apparatus may be utilized to quantify polishing toolor instrument data to thereby establish utility and efficacy forpurposes, for example, of comparison with standardized data.

The system thus includes associated software to control motioncomponents (motors and actuators) within the system. The software of anembodiment may typically be comprised of the following elements orequivalent controllers: a) An embedded control program, in an embodimentof the invention, developed for an 8051 microprocessor controller,written in C, b) a Graphical User Interface written in G using Active-XControls to communicate with peripherals, and c) various data processingscripts written in Visual Basic, which parse and organize the data. Forexample, embedded software in an embodiment of the invention consists ofinitialization routines including a) Programmable Counter Array Setup,b) Analog to Digital Converter Setup, c) I/O Port Setup, d) System ClockInitialization, and e) Serial Communication Setup. The embedded softwarewritten for this system dynamically and automatically controls the forceapplication hardware and is interrupt driven. Thus, it waits forexternal or internal events to execute certain subroutines upon calling.The interrupt driven routines include a) RS232 communication, b) forcecontrol hysteresis, c) programmed force update routine, and d) analog todigital conversion of the force sensor signal. Associated software waswritten in the G programming language and utilizes Active-X controls toactuate the motion components of the system including all linearactuators, rotation stages, and linear stages. The G program alsocommunicates with the microprocessor to set the programmed force,start/stop the force application, and call for the current programmedforce for troubleshooting the software. The G program also provides agraphical user interface for a user to interact with the system and settesting specifications such as contact time, contact force, and numberof passes. Final output for the roughness measurement component isprocessed with numerous scripts written in Visual Basic. A specific flowchart of the operation of the software is shown in FIG. 22, and aconcept map is shown in FIG. 23.

Thus, it is an object of the invention to provide an assemblage oftesting apparatus which are interrelated in a manner which enableshighly accurate assessment of the polishability of materials such asdental materials.

It is a further object of the invention to provide a series ofinstruments or apparatus which may be utilized independently one fromthe other yet which, in combination, provide the ability to carefullyassess the polishability of materials as well as the efficiency andadequacy and utility of polishing instruments used in a laboratory,clinical, or medical environment such as in the practice of dentistry.

Yet a further object of the invention is to provide a series ofinterrelated apparatus for polishing and conditioning solid materials todetermine the utility and efficacy of such materials as well as todetermine the utility and efficacy of instrumentation useful in theconditioning of such materials. Further, protocols associated with theinterrelationship of the apparatus are disclosed to enable replicationof conditions associated with the testing of materials and thepolishability thereof.

Another object of the invention is to provide transformational softwarewhich in combination with apparatus enables the preparation of samplesfor testing of polishability thereof and accurate and repeatablequantitative analysis of polishability and other parameters associatedwith such materials.

These and other objects, advantages and features of the invention areset forth in the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWING

In the detailed description which follows reference will be made to thedrawing comprised of the following figures:

FIG. 1 is a first oblique view of an embodiment of an initial surfacefinish preparation apparatus;

FIG. 2 is an isometric view of the apparatus or device of FIG. 1;

FIG. 3 is a second oblique view of the apparatus of FIG. 1;

FIG. 4 is a side elevation of the apparatus of FIG. 1;

FIG. 5 is a front elevation of the apparatus of FIG. 1;

FIG. 6 is an opposite side elevation of the apparatus of FIG. 1 oppositeto the view of FIG. 5;

FIG. 7 is an isometric view of a surface roughness measurementapparatus;

FIG. 8 is another isometric view of the apparatus of FIG. 7;

FIG. 9 is a perspective view of the apparatus of FIG. 7;

FIG. 10 is a side elevation of the apparatus of FIG. 7;

FIG. 11 is a top plan view of the apparatus of FIG. 7;

FIG. 12 is an oblique view of a height measurement apparatus comprisingan embodiment of the invention;

FIG. 13 is an isometric view of the apparatus of FIG. 12;

FIG. 14 is a front elevation of the apparatus of FIG. 12;

FIG. 15 is an isometric view of a gloss measurement apparatus whichcomprises an embodiment of the invention;

FIG. 16 is a perspective view of a polishing device testing apparatusembodiment of the invention;

FIG. 17 is a first side elevation of the apparatus of FIG. 16;

FIG. 18 is a further isometric view of the apparatus of FIG. 16;

FIG. 19 is a front elevation of the apparatus of FIG. 16;

FIG. 20A is a top plan view of a typical specimen disk for testing inaccord with the method, system and apparatus of the invention;

FIG. 20B is a side view of the disk specimen of FIG. 20A;

FIG. 21 is a flow chart illustrating the methodology of the practice ofthe invention and the multiple steps in the conduct of the polishingprotocol employed utilizing apparatus disclosed;

FIG. 22 is a flow chart associated with the polishing device testingapparatus illustrating the sequence of computer operations in controlthereof;

FIG. 23 is a further flow chart depicting a concept map of the polishingdevice testing apparatus; and

FIG. 24 is a series of graphs depicting typical test results from theconduct of the protocols associated with the testing apparatus of theinvention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIGS. 1-19 comprise embodiments of five separate stations utilized inthe practice of the method of the invention and constituting apparatusto enable the practice of multiple steps associated with the collectionof data potentially useful for standardizing and uniformlycharacterizing materials and the polishing of such materials, forexample, dental materials or restoratives. By way of example, compositematerials such as a combination of silica and bis-GMA including variousadditives and other formulations desirably will meet certainpolishability standards as well as reflective standards and the like.There are currently no specific quantitatively established standardswith respect to such materials. The mechanisms and protocols describedprovide a means to establish such characterizations in a reproduciblemanner. The various stations or apparatus are described sequentially inthe order in which they are typically used. Thus, the first device whichis described is an initial surface finish preparation apparatus and isdepicted in FIGS. 1-6 of the drawing. This device is used to initiallyprepare a desired, roughened surface or desired rough surface of aparticular material. The device is designed to enable the consistentreplication of the uniformity of surface of specific materials, such asdental filler materials referenced above when initially implanted androughly formed or shaped. Subsequently, modifications to the surface bya tool, such as a dental tool, can be evaluated as describedhereinafter.

Subsequent thereto, the roughness of the surface is quantified. This isdone using a second station or apparatus which constitutes a surfaceroughness measurement apparatus as illustrated in FIGS. 7-11.

As a third element in the establishment of the characterization of thematerial under investigation, a device for determination of the amountof material removed from the surface of a test specimen during anytesting procedure is utilized. This particular device may be used at anystage in the processing of the material. It may be used to determine theamount of material removed from the initial test specimen once a baseheight of the specimen is established as well as the amount removed uponthe completion of the series of steps used to characterize the material.This apparatus is identified as a height measurement apparatus and FIGS.12-14 depict an embodiment thereof.

Another important feature of materials of this nature is the gloss orreflectivity of the material. Apparatus and a protocol enable themeasurement of gloss of the specimen which has been placed through theother test stages associated with the practice of the invention. FIG. 15illustrates a gloss measurement apparatus.

The fifth and final apparatus in the protocol is a polishing devicewhich enables testing of the efficacy of polishing the material usingvarious polishing instruments or devices. Of additional interest, thepolishing device testing apparatus may be used not only to test thepolishability of specimens, but also to test the instruments that areused for the polishing of the specimen that has been prepared fortesting. FIGS. 16-19 of the drawing depict an embodiment of thisparticular element of the invention.

Upon characterizing the specific stations or apparatus, the method ofuse is discussed by way of example. A typical specimen is disclosed inFIGS. 20A and 20B. The overall stages in the testing protocol using theseparate devices are depicted in a flow chart as FIG. 21. FIG. 22illustrates the flow chart associated with the operation of softwarecontrolling one of the devices; namely, the polishing device. FIG. 23illustrates a functional flow chart associated with the polishingdevice.

Resultant comparative data and information are then illustrated in thecharts which comprise FIG. 24. Thus, the following description initiallyis directed to an explanation of the various stations or devicescomprising the physical embodiment of the invention including softwareassociated with those embodiments. This is followed by a specificrepresentative example of the practice of the invention.

Apparatus Stations

1. Initial Surface Finish Preparation Apparatus

Referring to FIGS. 1-4, there is illustrated an embodiment of thesurface finish preparation apparatus. The apparatus is designed to holda disk or cylinder specimen or sample and to polish one side of thesurface of that sample. The objective of the apparatus is to provide aninitial uniform surface finish which replicates, by way of example, adental filling or replacement material subsequent to its initial shapingby means of a dental finishing burr or the like. The surface, thus, hasa roughness associated with the particular dental tool that has beenused to roughly shape the dental filling or the like. The surface is inits initial form upon placement in the dental cavity.

The apparatus includes a support base 10 having a mounting post 12vertically extending therefrom. The mounting post 12 includes a guiderail 14 affixed along a vertical side thereof. The guide post 14 isaffixed to the post 12 by means of attachment brackets 16 and 18. Asample or specimen support assembly 20 is slidably mounted on the postby interaction with the guide rail 14. That is, the assembly 20 includesa housing 22 slidably mounted on guide rail 14 with a rod 24 associatedwith a cylinder within the housing 22 to provide for slidable adjustmentof the housing 22 on the rail 14 inasmuch as the rod 24 bottoms outagainst a stop 26 mounted at the lower end of the bracket 18. A manuallyadjustable knob 28 enables rough adjustment of the position of thehousing 22 and the mechanisms attached thereto.

A support plate 32 is attached to the housing 22 and moves verticallyupwardly and downwardly in response to the movement of the housing 22. Afirst bracket 34 supports a motor 36 having a drive shaft 38 connectedto a sample support 40. The sample support 40 is rotationally positionedwithin a ring bearing 42 mounted in a block 44 supported by a second orlower bracket 46 attached to the plate 32. The sample support 40supports a specimen 50 adhered at its distal or lower end. The motor 36is enabled to rotationally drive the shaft 38. The plate 32 may moveupwardly and downwardly in a vertical direction to position the specimen50 in opposition to a rotational platen 52 which may be rotationallydriven either the clockwise or counterclockwise sense on the base 10.The speed of the platen 52 will vary depending upon the material beingabraded, typically 5 to 510 rpm. However, the speed may be adjusted inany manner desired in order to test the particular material underinvestigation.

The platen 52 is typically covered with a removable disk of a gradedgrit covered material. For example, a carbide based grit may be utilizedon the disk. Specimen 50 is positioned so that it will engage thesurface of platen 52 and, more particularly, the grit material on thesurface of the platen 52 in a normal or perpendicular manner. However,the specimen 50 may be adjusted in an angular fashion to provide forengagement in a non-normal manner. The specimen 50 is rotated about itscylindrical axis in either a clockwise or counterclockwise direction byvirtue of the operation of the motor 36. The housing 22 may be raisedand lowered to thereby raise and lower the plate 32 vertically tocontrol the engagement of the specimen 50 with the surface of the platen52. The speed and force of engagement and other characteristicsassociated with the initial surface finish preparation protocol may becontrolled through appropriate software which controls the verticalposition of the specimen 50 as well as the rotational speed anddirection of the specimen 50 and/or the platen 52.

2. Surface Roughness Measurement Apparatus

Subsequent to preparation of the specimen 50 utilizing theaforedescribed surface preparation finish apparatus, it is appropriateto measure and record the roughness of the test specimen 50 as initialreference data with respect to the surface treatment protocol. It isthen used subsequently to collect surface roughness measurements afterthe material has been modified. These surface measurements are repeatedas necessary. Thus, the surface roughness measurements are made on thesample after preparation by the initial surface roughness preparationapparatus to get a baseline reading on the control region and the regionthat will be tested. At this point, they will (or should) be essentiallythe same. Then the specimen is polished and the roughness on the controland polished (test) regions are measured again. The control readingsshould be the same. If not, then something is wrong (e.g., misalignmentin the holder, etc.). This is a major attribute of the device. If thereis something wrong with the measurements, it will become clear from thecontrol readings, whether it be surface roughness, height, or gloss.This then serves as verification that the test region readings areactually from the tool being used on the specimen and not the act ofmaking the measurements. FIGS. 7-10 illustrate apparatus for providingan initial profile of the surface of the test specimen. Specifically, asupport base 60 includes a profilometer 62 which is mounted on anadjustable platform 63. The platform 63 is further mounted on a base 64which, in turn, is mounted on a horizontal positioning stage 66. Thus,the profilometer 62 may be adjusted upwardly and downwardly in height byrotation of a control knob 68 which adjusts the linkage assembly 70. Thehorizontal positioning assembly which supports the horizontal platform64 on the base 60 may be adjusted by turning the control knob 72 to movethe assembly thereby adjusting the stage 66 in an X direction or, inother words, toward the test specimen and the assembly associatedtherewith as described in greater detail hereinafter. Of course, theprofilometer 62 includes a shaft 74 and an associated profilometerstylus 76 which also move in the X direction in order for theprofilometer 62 to receive input regarding the profile of the testspecimen 50.

The stage 66 further includes a motorized Y-axis positioning arrangementcomprising a cylinder within a housing 78 which drives a motorized shaft80 to thereby position the stage 66 in the Y-axis direction.

A vertical support post 82 mounted on the base 60 supports a Z-axispositioning assembly 84. The Z-axis position assembly 84 is slidable inthe X direction in a bracket 86 mounted on the post 82. The Z-axisposition stage further includes an arm 88 which is moveable in the Zdirection. The arm 88 is attached to a slidable plate 90 mounted on aplate or bracket 92 attached to the post 82. The slidable bracket 90moves upwardly or downwardly in response to a rod 94 associated with acylinder within the cylinder housing 96 to thereby permit preciseadjustment of the arm 88 as the plate 90 is raised or lowered inresponse to manual or programmatic direction. A further support post 100supports a test specimen holder, clamp or collet 102 in which the testspecimen 50 is mounted on the support 40 positioned and maintained in asubstantially fixed position. The holder 102, however, may be rotatedwith respect to the post 100 by virtue of a rotational clamp mechanism106. The specimen 50 which was derived from the surface finishpreparation apparatus is thus mounted in the holder or clamp 102 and isattached to the same specimen support 40. Thus, the specimen 50 and itssupport 40, during the testing procedure, are maintained in the sameholder throughout the various test operations. Since support 40 remainsdimensionally unchanged, all data derived relates to the working ofspecimen 50.

The profilometer rod 76 includes a stylus at its outer end which isguided over the top, roughened surface of the specimen 50. Data isacquired by the profilometer 62 to provide a baseline of informationregarding the surface roughness and character of the surface of thespecimen 50 before final polishing. Data may also be acquired once thespecimen 50 is polished. Further, data may be acquired for roughened andpolished sections of the planar surface of the specimen such asdesignated in FIG. 20A. Again, the operation of the various motorizedelements of the device may be computer controlled for precisemeasurement and ultimate recording of data.

3. Height Measurement Apparatus

FIGS. 12-14 illustrate the height measurement apparatus. The heightmeasurement apparatus enables a measurement of the amount of materialremoved from the surface of the specimen 50 retained in the support,holder or mounting member 40 at any stage in the operation of the testprocedure. The height measurement apparatus includes a base 120 with asupport post 122 mounted on an XY positioning stage. The XY positioningstage includes an X-axis adjustment mechanism 124 and a Y-axisadjustment mechanism 126. A support bracket 128 is affixed to the postand supports an electronic height indicator 130 which includes an outputshaft 132 is operated by a linear actuator 134 mounted to the bracket128. The linear actuator 134 is used to raise and lower the probe of theshaft 132 of the electronic height indicator from and to, respectively,the surface of the specimen 50. A probe 136 extends from the heightindicator 130 and impacts upon the surface of the specimen 150. Thelength of the composite specimen 50 and its support 40 are retained uponthe planar surface 138 of the specimen holder assembly 140. The specimenholder assembly 140 includes a rotational platform 142 mounted on amotorized positioning stage 144 supported on the base 120. In thismanner the height of the specimen (indicating the amount of materialremoved) may be determined over the entire surface of the specimen.Positioning of the height probe with the X and Y axis positioning stageenables gross adjustment and the positioning stage assembly 144 enablesrotational adjustment. The data secured from the device may then bestored for graphing and computer analysis.

4. Gloss Measurement Apparatus

The gloss measurement apparatus is depicted in FIG. 15. The glossmeasurement device employs a gloss meter device 150 with a specialsupport assembly for the test specimen 50 including the specimen pylonsupport or rod 40. The rod 40 is supported over an aperture 152 of thegloss meter 150 by the positioning assembly which includes a holder 154for the rod or support 40 mounted on a vertical positioning slide 156affixed to a bracket 158 mounted on a horizontal positioning slide 160.The assembly is mounted on a plate or platen 162 on the top face of thegloss meter. Standard gloss meter readings may thus be obtained withrespect to polished and unpolished and partially polished specimenmaterials. Again, computer storage of the readout data is enabled.

5. Polishing Device Testing Apparatus

FIGS. 16-19 depict the above-identified apparatus. The apparatusincludes a support base 180. A first vertical support post 182 supportsa clamp assembly 184 at the top of the post 182. The clamp assemblyincludes an adjustable instrument support device 186 such as a device tosupport a dental instrument 190 or other such device used to modify thespecimen surface. The instrument support device 186 includes a clampingmember 188 which is designed to hold a dental instrument 190. Thepolishing device 190 includes a polishing burr or pad 192. The angle ofattack of the pad 192 may be adjusted rotationally by operation of theknob 194 for the support post 186. Thus, axial adjustment about the axis196 may be provided for the polishing instrument 190 as well as axialadjustment.

The apparatus further includes a second support post 198 with first andsecond spaced clamps 200 and 202 which, in turn, support a slidable testspecimen holder 204 which is designed to move in a Z or vertical axisdirection in response to the operation of a control motor 206 throughthe linkage 208. The test specimen holder 204 thus holds the testspecimen 50 and its mounting rod or support 40. The vertical positioningclamp 184 may then be adjusted downwardly so that the polishing face ofthe polishing device 192 may be positioned against or over the topsurface of the specimen 50. A programmed movement of the test specimenholder may then be utilized to engage the test specimen against thepolishing instrument. The post 198 is mounted on a horizontally moveableplatform 199 which moves in the Y direction in response to actuation ofa shaft or rod 201 responsive to a motorized horizontal positioningcylinder 203. Movement in the Y axial direction may be included bymodification of the platform 199 to move in Y or XY directions.

Thus, the specimen 50 may be subjected to engagement by the polishingpad or the like over its surface in the X direction at a controlledload. The instrument 190 may also be adjusted with respect to its angleof inclination. The knob 194 may be adjusted to change the attitude ofthe instrument 190 and the knob 194 may also be adjusted in order toaxially move the instrument 192 along the axis 196. The operation of themotor 206 as well as the horizontal positioning stage 203 may becomputer controlled.

FIG. 20A illustrates the top surface of a disk 50 which has beensubjected to working or measurements by various apparatus whenconducting the test protocols described hereinafter. FIG. 20Billustrates the side view of the polished disk. Initially, the roughnessof the surface is caused using the surface finish preparation apparatus.The roughness is then quantified by the surface roughness measurementapparatus. Height measurement indicates the amount of material removedby the roughness operation. Gloss may be measured subsequently or priorthereto. Finally, the polishing device is tested using the describedmachine and the polished region viewed or measured by means of theprofilometer or gloss measurement apparatus with the data obtainedcompared to the control (rough) portion of the specimen that has notbeen polished.

Referring to FIG. 20A, a control region 220 comprises the region 220 ofthe surface of the disk 50 which has been conditioned by the initialsurface preparation apparatus. The polished region 222 is the region ofthe surface of the disk initially conditioned by the initial surfacepreparation apparatus and then further conditioned by the polishingdevice testing apparatus.

FIG. 21 illustrates the steps that would normally be conducted using theapparatus. Initially, a sample 50 is prepared and mounted on a supportor rod 40. Initial surface preparation is performed using the initialsurface preparation apparatus. Subsequently, roughness, height, andgloss of the specimen surface is established on two regions of thesurface, which shall serve as the control and test region. Polishing isthen performed on the test region. The roughness, height, and gloss arethen measured in the same two regions at the same places on thoseregions and the resulting data for all measurements is processed. Themultiple steps of polishing followed by measurements of roughness,height and gloss in the control and test regions can be repeated asdesired.

FIG. 22 is a flow chart showing the multiple steps that may be utilizedfor control of the polishing apparatus. The system is initially startedand initialized. Importantly, a subsequent step is timing of the events.The force of the polishing instrument against the specimen surface isprogrammed and an initial test run is then caused to occur. Duringinitial test run, the time is controlled, the force is controlled andthe linear motion in the X direction is controlled. All the data isgathered for recordal and graphing. FIG. 23 is a simplified flow chartassociated with the operation of the polishing testing device. Itrepresents a flow of the various steps associated with FIG. 22.

Example of Test Protocol

In the description, reference may be made to various publications whichinclude specifications for materials such as dental materials as well asadditional background information and testing protocols associated withthe testing of dental materials. The description of embodiments of theinvention thus focuses upon dental materials inasmuch as such materialsare subject to quality control standards and consequently, measurementsassociated with those standards utilizing techniques and apparatus ofthe present invention that enable the creation of a higher degree ofconfidence in the assessment of such materials. By way of example andnot limitation, the following reference documents are cited:

-   ANSI/ADA Specification 27, “Resin-Based Filling Materials,” July    2005.-   ISO/DIS 4049 “Dentistry—Polymer-based filling, restorative and    luting materials,” 2008 Feb. 28.-   ISO 10650 “Dentistry—Powered Polymerization Activators”.-   C. S. Jones, R. W. Billington, and G. J. Pearson, “Laboratory study    of the loads, speeds and times to finish and polish direct    restorative materials,” Journal of Oral Rehabilitation, 2005 32:    686-692.-   C. S. Jones, R. W. Billington, and G. J. Pearson, “The in vivo    perception of roughness of restorations,” British Dental Journal,    2004 196: 42-45.-   Juliana Da Costa, Jack Ferracane, Rade Paravina, Rui Fernando Mazur,    and Leslie Roeder, “The Effect of Different Polishing Systems on    Surface Roughness and Gloss of Various Resin Composites,” Journal of    Esthetic Restorative Dentistry, 2007 19: 214-226.-   Tamayo Watanabe, Masashi Miyazaki, and B. Keith Moore, “Influence of    polishing instruments on the surface texture of resin composites,”    Quintessence International, January 2006 37 Number 1: 61-67.-   ASTM D 523-89, “Standard Test Method for Specular Gloss.” Annual    Book of ASTM Standards, Volume 6.01, “Paint—Tests for Chemical,    Physical, and Optical Properties; Appearance”.-   ASTM D 3980, “Practice for Interlaboratory Testing of Paint and    Related Materials.” Annual Book of ASTM Standards, Volume 6.01,    “Paint—Tests for Chemical, Physical, and Optical Properties;    Appearance”.-   Quirynen M., Bollen C. M., Papaioannou W., et al., “The influence of    titanium abutment surface roughness on plaque accumulation and    gingivitis: short-term observations,” Int. J. Oral Maxillofac    Implants 1996; 11:169-78.

In addition various national standards such as ANSI standards apply tothe materials of the nature considered to be candidates for assessmentusing the apparatus and methods of the present invention. Again by wayof example, the following standards can be augmented and proved andverified using the system and methods of the present invention.

General Requirements

Two dental composite materials shall be used along with a dentalpolishing instrument in this study. Heliomolar (agglomerated microfillcomposite, Ivoclar Vivadent, Inc.) and Esthet-X HD (hybrid, mini-fill,Dentsply Caulk, Inc.) are used in this example study along with the PDQ2polishing instrument (Item# P3138, Axis Dental, Inc.). However, anydental composite material and polishing instrument combination can beused with the described system.

For the tests in this protocol where water is referenced, deionizedwater shall be used in all instances.

Materials

Teflon molds, for the preparation of cylindrical specimens, 4 mmthick×15 mm in diameter. Note that the molds shall be vented such thatwhen pressure is applied to the molds excess material can flow out thevents.

Two metal plates, of sufficient area to cover one side of the mold.

White filter paper.

Glass microscope slides for use during polymerization.

Film, transparent to the activating radiation, e.g., polyester, 50±30 μmthick.

External Energy Source. In this study, the Optilux 501 (KerrCorporation) dental curing unit, with a 13 mm tip, shall be used as theexternal energy source. In general, the measured irradiance of theexternal energy source shall be above 300 mW/cm² as measured accordingto ISO 10650 “Dentistry—Powered Polymerization Activators.”

Hydraulic press.

Garolite, grade G-10, 15 mm in diameter, to be used to mount thecomposite material in the various apparatuses of the system.

Cyanoacrylate glue (e.g., Loctite 414, Loctite, Corp.) and primer (e.g.,Loctite 7471 Primer, Loctite, Corp.), to be used to secure the dentalcomposite material to the Garolite mounting material.

Initial Surface Finish Preparation Apparatus

Surface roughness measurement apparatus, (e.g., Surtronic 3+, TaylorHobson, Inc.). In this study, the settings for the surface profilometerwere the following: 2.5 mm traverse length, cut-off value of 0.25 mm,and traverse speed of 1 mm/s.

Height measurement apparatus. In this study, the electronic heightindicator (e.g., Mitutoyo 543 electronic indicator) was accurate to0.001 mm.

Gloss measurement apparatus, (e.g., Novo-Curve Glossmeter, RhopointInstrumentation LTD, East Sussex, UK). In this study, the glossmeter hada 60° geometry.

Polishing Device Testing Apparatus

Procedure

Preparation of Test Specimens

a. Test samples shall be prepared at laboratory temperature and humidity(approx. 23° C. and 50% humidity).

b. Cover one of the metal plates with the filter paper, followed by thepolyester film, and position the Teflon mold upon it.

c. Prepare the material in accordance with the manufacturer'sinstructions and fill the mold to a slight excess with the material(place the material as evenly as possible taking care to exclude airbubbles or voids).

d. Place a second piece of polyester film onto the material in the moldand cover this with the second metal plate. Apply 4000 psi of pressureusing a hydraulic press for 1 minute to displace any excess material(note that the molds shall be vented such that when pressure is appliedto the molds excess material can flow out the vents).

e. Replace the top metal plate with a glass slide (keep the polyesterfilm in place) and place the exit window of the external energy sourceagainst the glass slide and irradiate that section of the specimen forthe recommended exposure time.

f. Move the exit window of the external energy source to the sectionnext to the previous one, overlapping the previous section by half thediameter of the exit window, and irradiate for the appropriate time.Continue this procedure until the entire specimen has been irradiatedfor the recommended exposure time.

g. Replace the glass slide with the metal plate, turn the mold over, andreplace the bottom metal plate with a glass slide (keep the polyesterfilm in place) and place the exit window of the external energy sourceagainst the glass slide and repeat the irradiation procedure on thebottom side of the specimen.

h. After the irradiation procedure is complete, remove the specimen fromthe mold and use a drop of cyanoacrylate glue to attach the specimen toa 15 mm diameter Garolite rod. Note that the face of the Garolite rodshall be machined flat such that the deviation across the face is lessthan ±0.01 mm. Furthermore, the face of the Garolite rod shall besprayed with primer before the cyanoacrylate glue is dropped on thesurface. Also, one region of the Garolite rod shall be ground flatlengthwise to provide a reference point for mounting of the specimen inthe polishing, surface roughness, height measuring, and gloss measuringapparatuses.

i. After the specimen is attached to the Garolite rod, store it indeionized water in the water bath at 37±1° C. for 15 minutes.

Repeat the procedure for the desired amount of specimens.

Initial Surface Preparation

a. After a test specimen has been prepared according to the procedureabove, mount the specimen in the initial surface finish preparationapparatus (FIGS. 1-6) by securing the Garolite rod in the motorizedchucking device.

b. Once the specimen is properly mounted in the initial surface finishpreparation apparatus, the specimen shall be lowered such that it comesin contact with the abrasive paper (e.g., for this study, 120 gritsilicon carbide paper) mounted to the turntable of the apparatus. Thisshall be the initial position of the test specimen.

c. The turntable shall then be set to the desired rpm (e.g., for thisstudy 200 rpm) and turned on.

d. The motor of the motorized chucking device shall be set to thedesired speed and rotation and turned on. The motor shall be set suchthat the rotation of the specimen is counter to the rotation of theturntable with the abrasive paper.

e. Using the linear, motorized translation stage, the rotating specimenshall be lowered into the abrasive paper to a programmed distance (e.g.,in this study, a distance of 0.10 mm for the Heliomolar material and0.15 mm for the Esthet-X HD materials) at a programmed rate.

f. Once the total programmed distance is reached, the translation stageshall raise the specimen to the initial position at the start of theprocedure.

g. The motor of the motorized chucking device shall then be reversedsuch that the rotation of the specimen is in the same direction as theturntable with the abrasive paper. The speed of the motor shall be setto the same speed as the previous step.

h. Using the linear, motorized translation stage, the rotating specimenshall then again be lowered into the abrasive paper to a programmeddistance at a programmed rate and held for a programmed time.

i. Once the programmed time is reached, the translation stage shallraise the specimen such that it no longer contacts the abrasive paperand the apparatus shall be turned off.

j. The specimen shall be removed from the apparatus and dried. Theaverage Ra value shall then be obtained using the surface roughnessapparatus and the procedure set forth in the “Measurement of surfaceroughness” section below. The average Ra value of the surface of thespecimen shall be verified to the desired Ra±0.1 μm. If the average Ravalue is not within this window, the specimen shall be remounted in theinitial surface finish preparation apparatus and the procedure repeateduntil the desired starting value is obtained.

Surface Roughness Measurement

a. Mount the specimen in the surface roughness measurement apparatus

(FIGS. 7-11). The specimen shall be mounted such that the flat region ofthe Garolite rod is lined-up against the flat region of the mountingholder of the apparatus. This allows an individual specimen to bemounted in the same starting position each time it is placed in theapparatus. Furthermore, mounting the specimen in this position alignsthe flat region of the Garolite rod perpendicular to the path of theprofilometer stylus. This position shall be considered the referenceposition (0° position) and all subsequent roughness measurements shallbe made with respect to this position.

b. Once the specimen is properly mounted, a two-axis motorized stageshall be used to position the stylus of the profilometer over thedesired positions of the specimen. For the purpose of surface roughnessmeasurements, the specimen shall be divided into two halves (see FIG.20A). The top half shall be the test region and the bottom half thecontrol region, with the top half being nearest to the profilometer(FIGS. 7-11). Five readings shall be taken on the control region, andfive readings shall be taken on the test region of the specimen. Anadditional single-axis motorized stage mounted vertical to the two-axisstage shall be used to lower the stylus onto the specimen to takemeasurements and lift it back off again after the roughness measurementsare performed, such that no manual manipulation of the device isrequired and no marring of the surface of the sample occurs duringpositioning with the two axis stage. Thus, after proper mounting of thespecimen in the surface roughness measurement device, the computerprogram shall be initiated and the single-axis motorized stages shalllower the profilometer stylus onto the specimen. The two-axis motorizedstage shall then automatically move the profilometer stylus across thespecimen and a roughness reading shall be recorded to the computer. Thesingle-axis motorized stage shall then automatically lift the stylus offof the specimen, and the two-axis stage will move it into the nextmeasurement position. The computer program will repeat this processuntil five measurements are performed and recorded for both the controland test regions. The measurements shall be taken 3 mm from thecenterline dividing the control and test regions of the specimen, andeach group of five measurements shall be equally spaced 1.5 mm apart(FIG. 20A).

Height Measurement

a. Mount the specimen in the height measurement apparatus (FIGS. 12-15).The specimen shall be mounted such that the flat region of the Garoliterod is lined-up against the flat region of the mounting holder of theapparatus. This allows the specimen to be mounted in the same startingposition each time and shall be considered to be the reference position(0 degree position) for all subsequent measurements.

b. Zero the electronic height indicator and start the computer program.The program shall move the motorized rotation stage in 60 degreeincrements along the circumference of the specimen (1 mm in from theperimeter of the sample). At each 60 degree increment, the computerprogram shall automatically record the reading from the electronicheight indicator to an accuracy of 0.001 mm

Gloss Measurement

a. Mount the specimen in the gloss measurement apparatus (FIG. 15). Thespecimen shall be mounted such that the flat region of the Garolite rodis lined-up against the flat region of the mounting holder of theapparatus. This allows an individual specimen to be mounted in the samestarting position each time it is placed in the apparatus. The specimenshall be mounted such that the designated control region is centeredover the aperture opening of the glossmeter.

b. Once the specimen is properly mounted, it shall be lowered onto theface of the glossmeter, using the vertical slide, such that the centerof the control region is centered over the aperture opening of theglossmeter.

c. The glossmeter shall be calibrated according to ASTM D523. Threegloss readings shall be taken on the surface of the control region ofthe specimen and the mean shall be reported. If the range of the threegloss readings is greater than 2 gloss units, then additional readingsshall be taken and the mean shall be calculated after discardingdivergent results in accordance with the section on outliers in ASTMD3980.

d. Once the control region readings are completed, the specimen shall belifted off the face of the glossmeter using the vertical slide, movedinto position using the horizontal slide, such that the center of thetest region is centered over the aperture opening of the glossmeter, andlowered onto the face of the glossmeter using the vertical slide.

e. Three gloss readings shall be taken on the surface of the test regionof the specimen and the mean shall be reported. If the range of thethree gloss readings is greater than 2 gloss units, then additionalreadings shall be taken and the mean shall be calculated afterdiscarding divergent results in accordance with the section on outliersin ASTM D3980.

Polishing of Specimen

a. Mount the specimen in the polishing device testing apparatus (FIGS.16-19). The specimen shall be mounted such that the flat region of theGarolite rod is lined-up against the flat region of the mounting holderof the apparatus. This allows an individual specimen to be mounted inthe same starting position each time it is placed in the apparatus.

b. Set the speed of the hand piece. In this study, the speed of the handpiece was set at 17,500 rpm (research by Jones et al. 2005 showed thatthis is an optimum hand piece speed for polishing composite resins).

c. Using the computer program, set the load to be applied to thespecimen surface by the polishing device. The load shall be applied tothe specimen by the movement of a vertical slide that is attached to acomputer-controlled motor, which can move the specimen into thepolishing device until the programmed load is attained. In this study,the load that the specimen contacts the polishing device with was 30 g(research by Jones et al. 2005 showed that 20-30 g is an optimum loadfor polishing composite resins).

d. Once the specimen contacts the polishing device with the programmedload, the motorized positioning table shall move the specimen the fulldistance of the diameter of the specimen beneath the polishing devicefor programmed time period, while the computer-controlled motormaintains the programmed load. In this study, the programmed amount oftime was 10 seconds.

e. After the programmed test period is reached, the specimen shall beremoved from the polishing device testing apparatus, rinsed with astream of deionized water for five seconds, and dried with a stream offiltered, compressed air for five seconds. The surface roughness,height, and gloss of the test and control regions of the specimen canthen be measured and recorded as set forth above in the respectivesections of the protocol. This procedure of polishing the specimen forthe programmed time at the programmed load followed by measuring andrecording its surface roughness, height, and gloss can be repeated asmany times as desired by the operator (see flow chart in FIG. 21). Thevalues obtained for the control region for each of the measurements ofroughness, height, and gloss allow for quantification of the precisionfor the measurements at each step of the process.

Results

In this study, the polishing instrument passed over the test surface ofthe individual specimen twelve times, with each pass lasting 10 seconds.FIG. 24 shows the surface roughness and gloss measurement results forthe PDQ2 polishing instrument used on the two composites in this study.For the surface roughness measurements, each data point represents theaverage Ra value of five traces of the profilometer. At each step, thedata from the test region and from the control region is plotted. Forthe gloss measurements, each data point represents the average gloss ofthree readings of the glossmeter. At each step, the data from the testregion and from the control region is plotted.

The test protocols exhibited excellent consistency of quantitative dataincluding time dependent data. As a consequence, the repeatability oftest results enables one to quantitatively establish product parametersthat enable creation of usable standards.

While there have been set forth embodiments of the invention, it is tobe understood that the invention is limited only by the following claimsand equivalents thereof.

1. A dental materials standards testing method for determination of thepolishing characteristics of a surface of a solid specimen of acomposite dental material comprising the steps of: (a) providing a firstapparatus for imparting a measurable roughness to the surface of thematerial perform; (b) imparting a roughness to the said surface of saidspecimen using said first apparatus; (c) measuring the roughness of thesurface with a profilometer; (d) optionally collecting and measuring thequantity of material removed from said surface; (e) applying a polishingdevice to only a portion of the roughened surface to polish saidportion; and (f) measuring a parameter of the polished portion of thesurface selected from the group consisting of roughness and gloss of thematerial.
 2. The method of claim 1 wherein the step of measuring theroughness of the surface is performed by apparatus comprising: a base; aprofilometer mounted on a stand on said base, said stand adjustable inan XY plane and Z axis elevation, said profilometer including a stylussensor for engaging the specimen surface and measuring the roughnessupon movement in an XY plane.
 3. The method of claim 1 further includingthe step of measuring the gloss of the surface subsequent to at leastthe roughness step or the polishing step, or both.
 4. The method ofclaim 1 wherein the step of measuring the quantity of material removedis performed by apparatus comprising: a base; a specimen support standon the base; a support post; a transducer device mounted on the supportpost and a sensor for engaging the specimen surface and driving thetransducer in response to the height of the specimen.
 5. The method ofclaim 1 wherein the apparatus for polishing the composite dentalmaterial specimen and testing surface conditions of the specimen surfaceof said composite material comprises: (a) a first surface abrading standsaid stand including; (i) a rotationally mounted platen on said firststand for rotational movement about a first axis, said platen includingan abrasion surface; (ii) a sample containment device for said specimenmounted on the first stand; (iii) said sample containment deviceincluding a drive mechanism mounted on the first stand to drive thecontainment device in a direction generally normal to the first axiswherein said composite material specimen mounted by the samplecontainment device may be engaged with said abrasive surface, said drivemechanism further including a driver for independently rotating saidsample containment device about an axis generally parallel to said firstaxis; (b) a second roughness measurement stand, said second standincluding: (i) a positioning stage mounted on said second stand by amounting adjustment mechanism for independent horizontal movement ofsaid positioning stage on said second stand; (ii) a generally verticalmounting post on said second stand including a sample containment deviceclamping device for mounting a sample containment device, said clampingdevice rotatably attached to said mounting post and verticallyadjustably mounted on said mounting post to maintain said specimen insaid sample containment device directed vertically upward; (iii) aprofilometer having a generally horizontally projecting shaft with aprofile sensing stylus mounted on said shaft; (iv) a mounting platformon said stand for mounting said profilometer, said platform including anadjustment mechanism for moving said stylus over and onto said specimenin said sample containment device; (v) a profilometer drive mechanismfor moving said stylus to measure the roughness of the surface of saidspecimen whereby surface roughness data for said specimen is generatedregarding the surface profile of said specimen; and (c) a thirdpolishing device support stand including: (i) a generally verticaldental instrument support post with an upper end section, (ii) avertically adjustable clamp assembly attached to the upper end sectionfor holding a dental instrument with a dental composite modificationelement in a fixed position; (iii) a second support post mounted on saidthird stand with a horizontally and vertically adjustable clamp for aspecimen containment device for positioning said specimen in contactwith said dental instrument whereby said dental instrument may beoperated to polish the surface of said specimen.
 6. The method of claim5 including the step of controlling a load and a duration of engagementof said specimen and said dental instrument.
 7. The method of claim 5further including measuring material removal by a device comprising: (i)a fourth stand; (ii) a specimen support mounted on the fourth stand forsupporting said sample containment device containing a said specimen;(iii) a support post mounted on the fourth stand; (iv) a transducerdevice mounted on the support post of the fourth stand, and (v) a sensorfor engaging the specimen surface of said specimen and driving thetransducer in response to variations in the height of the specimensurface whereby the amount of material removed from the specimen surfaceis measured.
 8. The method of claim 5 further including measuring glossof said plished specimen by: (i) a gloss measurement device including agloss measurement sensor; and (ii) an adjustable sample containmentdevice clamp and support assembly whereby said specimen may bepositioned for readings by said gloss measurement sensor.
 9. The methodof claim 5 including collection of said surface roughness data and dataof the amount of material removed from the specimen surface and storageof said data in a storage device.
 10. The method of claim 9 furtherincluding comparing collected and stored data.